Valve mechanism



Feb.` l5, 193:8. C. E. suMMERs 2,108,514 l VALVE MEcHANIsM Filed Aug.V 16, 1955 Patented Feb. 15, ,21938 u NiTED STATES- rATEn-r otr-i vALvEMECHANISM Caleb E. Summers, Pontiac, Mich., assignor to General MotorsCorporation,- Detroit, Mich., a

corporation ot Delaware Application August 16, 1935, Serial `lzl'o.36,465 9'c1aims. (ci. 12s- 9m .This invention has' to do with. hydraulictakeup mechanism especially adapted for use in the valvemechanism ofinternal combustion engines. In the form illustrated the take-upmechanism is embodied in a valve tappet of the type usually ably mountedin the cup and loosely connectedV to a thrust transmitting member whichserves to control the ow of uid into and out ofthe hydraulic chamberformed between the piston 'and the bottom of the cup. -Means isprovidedto yieldingly urge the thrust-transmittingmember in a direction topermit i'low, but,upon ap-f .2d plication of thrust to the valveoperating system the flow is shut off and the uid inthe chamber acts' asa Iixed abutment during the .balanceof the valve operating cycle.

When the' valve operating pressure is removed l from the system thethrust-transmitting member is moved to a position to permit flowofiiuidAinto and out of the bottom of the hydraulic ,f

chamber to compensate 'for` variations in the length of the train ofmechanism due 'to expansionand contraction of the parts orothercauses.'v v

The principal advantages of the invention are the controllable lash andpositive action of the means controlling ow of fluid into and outa ofthe hydraulic chamber. It has been undesrable to have tappets-whichtake-up to no lash since a slight eccentricity of the base circles ofthe cam tends to makethe valve ride, 'thereby lessening its pressure onits seat-,.interferingwith 46 heat flowand putting extra duty andharder' wearon the tappet. The improved construction is alsocharacterized byabsence of ball check 4valves, or the like, whichoperate with very light Ipressure, and are objectionable since theslightl '45 est obstruction holds them off their seat.

Other objects and advantages of the invention will be apparent in the`course oi the followingdescription in whichz' Figure 1 is a sectionalView through a portion 50' of 'an automobile engine showing theconstruction and location` of the device.l Figure 2 is 'an enlargedsectional View of a f portion of the device. 1

Figure 3 is asection on lin'e 3 3 of Figure 2.

55 In Figure 1 there is shown a portion of a con-J-N `and the otherconsists together with thepi'ston I9 to which it is loosely lventionalautomobile engine provided with cam-4 shaft ||l having cam I2 thereonadapted to pef riodically lift the'` tapp'et designated I4 in itsentirety. The tappet comprises telescoping thrust devices one of whichVconsists of the cup I6, 5

' of thrust member I8,

connected. To accomplish this the piston I9 is preferably apertured atto loosely receive the lower reduced portion 2| of the thrust mem- 10ber I8 and sleeve '21| is a press-fit upon the extension 2|. The sleeve`24 is provided at its upper end with an outturned flange 26 formed withradial grooves 21 asbest shown in Figure 3 which provides passagescommunicating with the 1 5 clearance about the member I8. The spacebetween the upper surface of the flange 26 and the shoulder 28 formed atthe junction of the reduced portion 2| with the main portion of thethrust member I8 is slightly greater than the- 20 thickness of the endwall of piston I9, thereby permitting a slight relative movement betweenthe thrust member Vand piston. The opposed surfaces of the shoulder 28and the piston when brought into contact with eachother seal thepassages from the hydraulic lchamber constituted by the grooves V21 andthe clearance between the extension 2| andthe aperture -in the piston.In the bottom of the cup is located the springi 1 30 which` reactsagainst the iiange 26 -so as to 30 urge the thrust member upwardly totake up4 lash and at the same time tend to separate the sealing surfacesat the shoulder'28 to permit fluid to enter or leave'the hydraulicchamber 'to compensate for variations in lash due to ex- 35- pansion orcontraction of the parts of the valve mechanism.

`32 indicates a tubularguide lmember which may b e formed of sheetmetal, and is preferably a presst withinthe upper portion .of 'the cup,40 the lower portion of the enlarged portion 34 of the guide resting onshoulder 36, provided in the cup member I6. y

While the upper portion of the thrust member |8,could, if desired, beshaped to directly engage 45 the valve stem, I have preferred to employan adapter 3,8 which is seatedon the member I8.

` At is shown the valve with which the adapter 38 is inoperativeengagement, and 42 indicates the spring normally urging the valve on itsseat. In order to insure a supply of oil to theA tappet. the cup I6 -ispreferably apertured at 44, and oil is supplied to the tappet throughpassage 46 which is preferably `at all times in communication with a.reduced annular portion I8 of the 55 spring 42.

spring 3II urges the thrust member I8 and' adapt.

er 38 upwardly into engagement with the end of the valve stem 40. Underthese conditions the passage leading to the hydraulic chamber beneaththe piston will be open, as illustrated.

When the cam starts its lifting movement, cup I4 is raised and with itthe piston I9, while the thrustmember I8 and its associate parts areheld against upward movement by the action of the valve spring 42. As aconsequence the flow of oil from the hydraulic chamber is shut off byengagement of thesurfalcesat 28 and from then on throughout the valveopening-and closing movement the oil in the chamber acts as a solidabutment to transmit thrust. When the valve reaches its seat and thesystem is relieved of the pressure of the valve spring 42, spring 30comes into play and4 urges the cup` I6 downwardly against the basecircle of the calm and at the same time urges the thrust member I8 andits associated parts upwardly into engagement with the end of the valvestem, thereby opening the passage beneath shoulder 28', so that if therehas been slight leakage or other cause for adjustment as, for example,contraction of the parts owing to cooling, the increased volume of thehydraulic chamber due to the greater separation ofthe` piston I9 and thecup I6 causes oil'to be drawn into the hydraulic chamber.

An advantage of the construction resides in the fact. that the lash inthe valve operating system may be made whatever value -is desired byadjusting the distance between the upper surface of ilange 2i and theshoulder 28.

It will be understood that the described actionA takes place during eachoperation of the, valve gear, and that the tappet operates as a positivepump to draw oil into the hydraulic chamber each time the valve seatsindependently of any pressure from the oiling system, then as soon asthe cam. starts to lift the tappet the valve at 28 is closed with allthe force of the main valve The reservoir inside the cup I6 and belowthe openings 44 ,is suiiicient to supply immediately the oil required toput all tappets in perfect adjustment when the engine is started upaftera 1ong` period of idleness even though the thrust members I8 underpressure of the valve spring have naturally settled down so that thereduced portions 2l rest onthe bottoms of the tappets. The provision forsuch engagement provides a safety factor to permit operation oi theengine even though the tappets should in some manner become empty ofoil.

Since the hydraulic chamber is vented vupon each operation,.opportunityis presented for the escape of air should` any be present. However, thesliding t between the cup I6 and its guide and between the enlargedportion of thrust member III and its guide provide for escape of air inthe reservoir above the piston so that there is little likelihood of airentering the hydraulic chamberl.

While the invention is described in connection with a tappet forinternal combustion engines it I9 in the cup I6 will .will'be apparentthat it is of utility Wherever a hydraulic take-up device may be founddesirable.

Iclaim:

1. In hydraulic take-up means the combination of telescoping thrustdevices, one of said devices being adapted to rest on a, body of fluidcontained in the other, and valve means associated with said last-nameddevice for controlling the passage of iiuid to and from said body andincluding a member having a portion exposed outside of said telescopingthrust membersso as to receive thrust and transmit it to one of saidmembers and yielding meansnormally urging said valve means toward openposition.

2. An hydraulic valve tappet comprising a cup, an apertured pistonslidably mounted in the cup, a thrust member passing loosely through theaperture in the piston, means loosely connecting the thrust member andpiston and adapted to permit limited relative movement therebetween,means yieldingly urging the thrust member out of the cup, andcooperating sealing surfaces on the thrust member and piston broughtinto play upon inward movement of the thrust member for sealing thepassage between the piston and thrust member constituted by the loose tof the thrust member, in the aperture in the piston.

3. In Vhydraulic take-up mechanism the combination 'of a cup, a pistonslidable in the cup,- said piston being provided with a passage adaptedto permit 'ow of fluid from one side of the piston p to the other,thrust transmitting means arranged ton so as to permit relative movementof said means and piston, valve means actuated by relativemovement ofthe piston and thrust transmitting means for closing said passage, andmeans yieldingly urging said thrust transmitting means in a direction toopen said valve means. 4. In hydraulic take-up mechanism the combinationof a cup, a piston member slidable in the cup, said piston member havinga bore therein, 'a` thrust transmitting member arranged in seriesthrust-transmitting relation with said cup and piston and extendingthrough said bore and fitting loosely therein so as to permit passage offluid therearound, one of said members having abutments thereon adaptedto engage the other, said abutments being spaced apart to permitlimited' independent movement of said members inthe line of thrust. oneof said abutments and the other, of said members being provided withmating surfaces adapted to engage to prevent passage of fluid throughsaid bore, and means for yieldingly urging one of said members in adirection to hold said surfaces out of sealing engagement.

, piston relative to the thrust member, and means.

for yieldingly urging the cup.

l 6. In hydraulic take-up mechanism the combination of a cup, a pistonslidable in the cup,

the thrust member out of said piston having a bore therein, a thrusttransmitting member extending through said bore and having a looselateral t therein to permit passage of fluid through said bore aroundsaid thrust member, means limiting the endwise movement of said thrustmember with respect to said pist0n, said piston and member beingprovided with cooperating valve means adapted to be closed by inwardmovement of the thrust member relative to the piston or by outwardmovement of the piston relative toI the thrust member, means foryieldingly urging the thrust member out of the cup, said cup beingprovided with guiding meansv Abody comprising a valve member arranged totransmit thrust from one of said members to said element, and means foryieldingly urging said valve member toward open position.

8. In hydraulic take-upmechanism for use in operating the valves ofinternal c ombustion engines and the like, the combination of anoperating member, an operated member, and means for transmitting thrustfrom the operating member to the operated member comprising telescopingthrust devices, one of said devices being adapted to rest' on a body offluid contained in the other,

and valve means controlling the passage of fluid to and from said bodyand including a relatively y movable valve member interposed betweensaid uid supported thrust device and one of said members so as totransmit thrust therebetween.

t 9. In hydraulic take-up mechanism for use in operating the Valves ofinternal combustion engines and the like, the combination of anoperating member, an operated member, means for transmitting thrust fromthe operating'member members so as to transmit thrust therebetween,

and means normally urging said. valve means toward open position.

